The primary purpose of the Transgenic/Knockout Mouse Shared Resource (TG-KO) is to provide an efficient and economical means for producing genetically modified mice for members of the Virginia Commonwealth University (VCU) Massey Cancer Center (MCC). Genetically modified mice (including transgenic mice, in which customized genes are introduced into the genome, and knockout/knock-in mice, in which endogenous genes within the mouse genome are specifically inactivated or modified) have become an indispensable tool in cancer research. The utility of such models ranges from studies of the basic biology of tumorigenesis and progression to the creation of genetically accurate tumor models for the evaluation of novel therapeutic approaches. The TG-KO offers the following services: (1) transgenic mouse production, (2) knockout/knock-in mouse production, (3) mouse line rederivation by embryo transfer, (4) embryo and sperm cryopreservation, (5) tail DNA preparation and genotyping, and (6) management ofthe IVIS Spectrum optical imaging facility in the Molecular Medicine Research Building (MMRB) barrier vivarium. In addition, the TGKO provides extensive consultation on many aspects of transgenic/knockout mouse technology, including overall experimental design, vector design, budgeting for mouse colony maintenance, and preparation of applications to the lACUC for the use of laboratory animals in research. In addition, the TG-KO staff provides instruction on overall colony management, including breeding strategies, weaning, ear punching, and tail DNA isolation. During the period from Jan. 1, 2010 to December 31, 2010, the TG-KO provided services to 36 different investigators, 19 of whom were MCC members. This included 2 transgenic mouse projects for 2 investigators, 7 knockout mouse projects for 6 investigators, 3 cryopreservation projects for 3 investigators, 54 mouse line rederivations for 18 investigators, and 479 genotyping reactions for 4 investigators.